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Remove a static allocation in C++ exceptions support code in JS #12039

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Merged
merged 4 commits into from
Aug 25, 2020
Merged

Remove a static allocation in C++ exceptions support code in JS #12039

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8fa376d
Avoid a static allocation in JS exceptions code, which also makes it …
kripken Aug 25, 2020
7b812df
fix
kripken Aug 25, 2020
84d34ca
wip [ci skip]
kripken Aug 25, 2020
269a989
fix
kripken Aug 25, 2020
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17 changes: 8 additions & 9 deletions src/library_exceptions.js
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@
var LibraryExceptions = {
$exceptionLast: '0',
$exceptionCaught: ' []',
$exceptionThrowBuf: '0',

// Static fields for ExceptionInfo class.
$ExceptionInfoAttrs: {
Expand Down Expand Up @@ -395,7 +396,7 @@ var LibraryExceptions = {
// unwinding using 'if' blocks around each function, so the remaining
// functionality boils down to picking a suitable 'catch' block.
// We'll do that here, instead, to keep things simpler.
__cxa_find_matching_catch__deps: ['$exceptionLast', '$ExceptionInfo', '$CatchInfo', '__resumeException'],
__cxa_find_matching_catch__deps: ['$exceptionLast', '$ExceptionInfo', '$CatchInfo', '__resumeException', '$exceptionThrowBuf'],
__cxa_find_matching_catch: function() {
var thrown = exceptionLast;
if (!thrown) {
Expand All @@ -416,12 +417,10 @@ var LibraryExceptions = {
#if EXCEPTION_DEBUG
out("can_catch on " + [thrown]);
#endif
#if DISABLE_EXCEPTION_CATCHING == 1
var thrownBuf = 0;
#else
var thrownBuf = {{{ makeStaticAlloc(4) }}};
#endif
{{{ makeSetValue('thrownBuf', '0', 'thrown', '*') }}};
if (!exceptionThrowBuf) {
exceptionThrowBuf = _malloc(4);
}
{{{ makeSetValue('exceptionThrowBuf', '0', 'thrown', '*') }}};
// The different catch blocks are denoted by different types.
// Due to inheritance, those types may not precisely match the
// type of the thrown object. Find one which matches, and
Expand All @@ -432,8 +431,8 @@ var LibraryExceptions = {
// Catch all clause matched or exactly the same type is caught
break;
}
if ({{{ exportedAsmFunc('___cxa_can_catch') }}}(caughtType, thrownType, thrownBuf)) {
var adjusted = {{{ makeGetValue('thrownBuf', '0', '*') }}};
if ({{{ exportedAsmFunc('___cxa_can_catch') }}}(caughtType, thrownType, exceptionThrowBuf)) {
var adjusted = {{{ makeGetValue('exceptionThrowBuf', '0', '*') }}};
if (thrown !== adjusted) {
catchInfo.set_adjusted_ptr(adjusted);
}
Expand Down